Drillable bridge plug

ABSTRACT

The invention is an improved bridge plug device which uses shearable &#39;&#39;&#39;&#39;O&#39;&#39;&#39;&#39; rings as appropriate retainers to maintain the assembled component parts in proper relationship before the bridge plug is used in an earth well or the like. The device of this invention is more simply manufactured and assembled than known bridge plugs which utilize shear pins to hold the component parts in position.

United States Patent [191 Pitts Oct. 7, 1975 DRILLABLE BRIDGE PLUG [75]Inventor: Charles A. Pitts, Wichita Falls, Tex.

[73] Assignee: The Dow Chemical Company,

Midland, Mich.

22 Filed: July 26, 1974 21 Appl. NO; 492,119

[52] US. Cl 166/134; 166/135 [51] Int. Cl. E21B 23/06; E21B 33/129 [58]Field of Search 166/135,134,123125, 166/206, 212, 216, 217, 237

[56] References Cited UNITED STATES PATENTS 3,091,293 5/1963 Fry 166/1233,115,186 12/1963 Kline 166/135 3,250,331 5/1966 Boyle 166/135 X3,303,885 2/1967 Kisling... 166/135 X 3,631,924 1/1972 McGill... 166/1343,631,925 l/1972 Nutter.... 166/134 3,631,927 1/1972 Young 166/134Primary Examiner-David H. Brown Attorney, Agent, or Firm-Earl D. Ayers[57] ABSTRACT The invention is an improved bridge plug device which usesshearable 0 rings as appropriate retainers to maintain the assembledcomponent parts in proper relationship before the bridge plug is used inan earth well or the like. The device of this invention is more simplymanufactured and assembled than known bridge plugs which utilize shearpins to hold the component parts in position.

3 Claims, 2 Drawing Figures US. Patent Oct. 7,1975

DRILLABLE BRIDGE PLUG BACKGROUND OF THE INVENTION This invention relatesto bridge plugs and particularly to drillable bridge plugs for use inearth wells.

Drillable bridge plugs are well known in the well drilling and servicingarts. However, the usual practice is to employ shear pins to hold thevarious components of the bridge in predetermined relationship withrespect to each other. This use of shear pins requires both precisionsizing of the pins and the bores into which they fit, but also requiresprecise alignment of parts when the pins are inserted.

OBJECTS OF THE INVENTION A principal object of this invention is toprovide an improved drillable bridge plug which is easy to assemble.

Another object of this invention is to provide an improved, economicalto manufacture, drillable bridge plug.

STATEMENT OF INVENTION In accordance with this invention there isprovided a drillable bridge plug comprising, disposed about a centralmandrel, upper and lower slip elements, upper and lower slip cones, apacking element disposed between the cones, a fixed position bottomplate and a movable top plate positioned to bear against the upper slipelements. The top plate, upper slip elements, lower slip cone and lowerslip elements are held in position until the bridge plug is to be set byshearable rings disposed in grooves along the outer surface of themandrel and the inner surface of the parts named.

The bridge plug is set in the well bore by using an explosive settingtool whereby the outer part of the setting tool moves downwardly againstthe top plate of the plug while the mandrel is held in position by atension stud which is connected to the setting tool. The down wardmovement of the top plate moves the slips and cones and that movementcompresses and expands the packing element to seal it against the wellcasing or well bore wall.

BRIEF DESCRIPTION OF THE DRAWING The invention, as well as additionalobjects and advantages thereof, will best be understood when thefollowing detailed description is read in connection with theaccompanying drawing, in which:

FIG. 1 is a side elevational view, partly in section, of a drillablebridge plug in accordance with this invention, and

FIG. 2 is a sectional view taken along the line 22 of FIG. 1.

DETAILED DESCRIPTION OF THE DRAWING Referring to the drawing, there isshown a drillable bridge plug, indicated generally by the numeral 10,comprising an elongated inner mandrel 12 having a lower end 14 whoseouter peripheral surface is threaded and an upper end 16 having acentrally disposed threaded bore 18 extending into it.

The outer peripheral surface of the mandrel 12 is its largest diameterat its upper end part, then is reduced in diameter somewhat from thereuntil near the lower end of the mandrel 12 where the threaded part is ofsomewhat reduced diameter.

A top plate 22 having an axial bore 26 sized to fit closely but slidablyaround the larger diameter part of the mandrel 12. The top plate is heldin position during assembly and until the plug is to be set by 0 ring 24which fits in opposed grooves in the outer surface of the mandrel andinner wall of the top plate, respectively.

An upper slip member 30 having a horizontally toothed outerconfiguration and an inner wall part adapted to slide along the outersurface of the mandrel l2 abuts against the lower surface of the topplate 22.

The inner wall part of the slip member 30 which slides over the mandrel12 extends along a minor part of the length of the member 30 and then,tapers outwardly at 56, for example, after a grooved part 66 permitsinsertion of the 0 ring 28 in a groove in the mandrel 12, until the slipmember is rather thin at the end thereof which is remote from the topplate 22.

The slip member 30 contains a plurality of symmetrically arrayedlongitudinal slits extending along its length and from the inner surfaceto near the toothed outer part of the member 30.

An upper cone member 32 having an outer peripheral surface adapted tobear against the tapered undersurface part 56 of the slip member 30,abuts against the upper end of the longer reduced outer diameter part ofthe mandrel 12. The lower end of the upper cone member 32 abuts againstthe upper end of the packing element 36 which fits slidably about theouter peripheral surface of the mandrel 12.

The packing element 36 is illustrated as having tapered ends, but endswhich are perpendicular to the longitudinal axis of the plug are alsopractical.

A lower cone member 38 fits around the mandrel 12 with its upper endabutting against the lower end of the packing element 36. The conemember 38, like the cone member 32, has a tapered outer surface alongwhich the tapered undersurface 54 of the lower slip member 44 is adaptedto move.

The cone member 38 is held in position abutting against the packingelement 36 by an 0 ring 40 which rides in a groove in the mandrel andabuts against a recessed part of the lower end of the cone member 38.

The lower slip member 44, of the same form as the upper slip member 30,fits around the mandrel 12 with its tapered surface 54 overlapping thetapered outer surface of the cone member 38. The slip member 30 haslongitudinal slits 50 which are arrayed as the slits 48 are in slipmember 30.

Upward movement of the slip member 44 is prevented by the 0 ring member46 which fits into a groove in the outer surface of the mandrel andabuts against a recessed part of the member 30.

A retaining base member 20 is screwed over the threads 52 of the furtherreduced diameter lower end of the mandrel I2.

OPERATION The bridge plug of this invention is assembled by slipping thetop plate 22 along the mandrel 12 with the 0 ring 24 in place so thatthe groove 26 extending downwardly from its top surface passes over thering 24. The plate 22 is then retained by the ring 24 bearing againstthe wall of the groove 26.

The upper slip member 30 slides over the mandrel 12 and bears againstthe top plate 22. The slip member 30 is then held in place by insertingthe 0 ring element 28 into the groove 64 in the mandrel through the openended groove 66 in the inner part of slip member 30.

The upper cone member 32 then slips over the mandrel 12, coming to restagainst the shoulder 34 between the larger and smaller diameter wallparts of the mandrel 12.

The packing element 36 is then slid over the mandrel 12 to bear againstthe end of the upper cone member 32.

The lower cone member 38 is then slid over the mandrel 12 to abutagainst the lower end of the packing element 36 and is held in place byan ring 40 in a groove in the mandrel 12 at the lower end of member 38.

The lower slip member 44 slips over the mandrel 12 with its taperedsurface 54 bearing against the inclined surface of the conical member38. Further advancement of the slip member 44 is prevented by the 0 ring46 in a groove in the outer surface of the mandrel 12.

The base element 20 is then screwed onto the threaded lower end of themandrel l2, bearing against the lower end of the lower slip member 44.

The bridge plug of this invention may be assembled in about ten minutesas compared with about an hour for a bridge plug using shear pins tohold its assembled parts in position. In addition, the cost ofmanufacture of this bridge plug is reduced over a similar bridge plugutilizing shear pins because no precision drilling or fitting for usingshear pins is required.

Also, the shearing pressure of0 rings is more uniform than is the casewith shear pins, so the operation of the bridge plug of this inventionis more predictable.

The bridge plug is lowered down the bore hole, usually within a stringof easing, on a cable to which is coupled an explosively actuatedsetting tool, as is well known in the art.

The setting tool (not shown) has a stud at its lower end which iscoupled to the threaded bore 18 at the upper end of the mandrel 12. Thesetting tool also has an outer rim part which is adapted to be drivendownwardly with respect to the above mentioned stud on firing of theexplosive material in the setting tool.

Once the explosive material in the setting tool is fired, the rim partof the setting tool forces the top plate downwardly, shearing the 0rings 28 and 40 as the upper slip member 30, upper cone 32, packingelement 36 and lower cone 38 are driven downwardly with the top plate 22by the rims of the setting tool.

As relative movement occurs between the slip members and cones, thepressure causes the slip members to break along the slots 48, 50,segmenting the advancing slip elements. The setting tool, once thepacking element 35 and slip members 30, 44 have advanced to set thebridge plug 10 is separated from the bridge plug by breaking the tensionstud which has been attached to the mandrel 12 during the settingoperation.

Because precision fits are not required with most parts of the bridgeplug 10, most parts may be cast rather than forged or machined, furtherreducing the manufacturing costs of the unit.

What is claimed is:

1. A bridge plug for use in well bores and the like comprising anelongated mandrel having an upper end including setting tool attachmentmeans, and a lower end having threads on its outer peripheral part, abase element, said base element being threadedly engaged with saidthreads on said mandrel, and a lower slip member, lower cone member,packing element, upper cone member, upper slip member and top platebeing disposed around said mandrel in the named order, said packingelement having ends each of which abut against one of said cone members,each cone member having a tapered surface which tapers towards saidmandrel from that part of its outer surface which is adjacent to saidpacking element, each of said slip members having a tapered undersurface adapted to bear against the tapered surface of its adjacent conemember, said lower slip member abutting against said base element andsaid upper slip member abutting against said top plate, an array of 0rings, each of said 0 rings lying in a groove in the outer periphery ofsaid mandrel and abutting against an upper or lower inner edge of aretained part of said plug, said grooves being so disposed along saidmandrel that, until the 0 rings contacting said upper slip member andsaid lower cone member are sheared, downward movement of said upper slipmember, upper cone member, packing element and lower cone member isprevented.

2. A bridge plug in accordance with claim 1 wherein said 0 rings eachcontact an edge surface of the adjacent part which surrounds saidmandrel.

3. A bridge plug in accordance with claim 1 wherein said upper conemember abuts against a shoulder on the outer peripheral surface of saidmandrel.

l l =l I

1. A bridge plug for use in well bores and the like comprising anelongated mandrel having an upper end including setting tool attachmentmeans, and a lower end having threads on its outer peripheral part, abase element, said base element being threadedly engaged with saidthreads on said mandrel, and a lower slip member, lower cone member,packing element, upper cone member, upper slip member and top platebeing disposed around said mandrel in the named order, said packingelement having ends each of which abut against one of said cone members,each cone member having a tapered surface which tapers towards saidmandrel from that part of its outer surface which is adjacent to saidpacking element, each of said slip members having a tapered undersurface adapted to bear against the tapered surface of its adjacent conemember, said lower slip member abutting against said base element andsaid upper slip member abutting against said top plate, an array of 0rings, each of said 0 rings lying in a groove in the outer periphery ofsaid mandrel and abutting against an upper or lower inner edge of aretained part of said plug, said grooves being so disposed along saidmandrel that, until the 0 rings contacting said upper slip member andsaid lower cone member are sheared, downward movement of said upper slipmember, upper cone member, packing element and lower cone member isprevented.
 2. A bridge plug in accordance with claim 1 wherein said 0rings each contact an edge surface of the adjacent part which surroundssaid mandrel.
 3. A bridge plug in accordance with claim 1 wherein saidupper cone member abuts against a shoulder on the outer peripheralsurface of said mandrel.